invisible barrel of rum

I ran into a bunch of other people cosplaying Mephisto Pheles while looking for the Ao no Exorcist photoshoot, and we ended up wandering around together. And then we got bored and I borrowed someone's cape for Captain Morgan poses, having run out of more attractive ideas.

Inb4 "IRON YOUR COSTUME". I did. And then I frumped around in a convention center all afternoon. I don't know how to make quilter's cotton not wrinkle. If you have any suggestions, please enlighten me.